Elements represent most of the "markup" and structure of the
document. They contain both the data for the element itself
(element name and attributes), and any contained nodes, including
document text (as children).

Elements may have Attributes associated with them; the API for this is
defined in Node, but the function is implemented here. In general, XML
applications should retrive Attributes as Nodes, since they may contain
entity references and hence be a fairly complex sub-tree. HTML users will
be dealing with simple string values, and convenience methods are provided
to work in terms of Strings.

DeferredElementImpl inherits from ElementImpl which does not support
Namespaces. DeferredElementNSImpl, which inherits from ElementNSImpl, does.